Topic
Symmetry (physics)
About: Symmetry (physics) is a research topic. Over the lifetime, 26435 publications have been published within this topic receiving 500189 citations. The topic is also known as: symmetry (physics) & physical symmetry.
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TL;DR: In this article, the equations of hydromagnetics appropriate for an incompressible inviscid fluid of finite electrical conductivity are considered in case the magnetic fields and the fluid motions have symmetry about an axis.
Abstract: The equations of hydromagnetics appropriate for an incompressible inviscid fluid of finite electrical conductivity are considered in case the magnetic fields and the fluid motions have symmetry about an axis By using a known theorem that a solenoidal vector field can be expressed as a superposition of a poloidal and a toroidal field, the equations are reduced to four equations for four governing scalars. In the limiting case of infinite electrical conductivity, a general relation is derived which includes, as special cases, the known theorems on force-free fields, isorotation, and conditions for hydrostatic equilibrium. Some integral relations which follow from the four equations are also derived.
145 citations
TL;DR: In this paper, the authors derive positivity bounds for scattering amplitudes of particles with arbitrary spin using unitarity, analyticity and crossing symmetry, which imply the positivity of certain low-energy coefficients of the effective action that controls the dynamics of the light degrees of freedom.
Abstract: We derive positivity bounds for scattering amplitudes of particles with arbitrary spin using unitarity, analyticity and crossing symmetry. The bounds imply the positivity of certain low-energy coefficients of the effective action that controls the dynamics of the light degrees of freedom. We show that low-energy amplitudes strictly softer than O(p
4) do not admit unitary ultraviolet completions unless the theory is free. This enforces a bound on the energy growth of scattering amplitudes in the region of validity of the effective theory. We discuss explicit examples including the Goldstino from spontaneous supersymmetry breaking, and the theory of a spin-1/2 fermion with a shift symmetry.
145 citations
TL;DR: In this article, a slave-boson theory for the finite doping model at finite doping was developed, which respects an SU(2) symmetry, a symmetry previously known to be important at half filling.
Abstract: We develop a slave-boson theory for the $t\ensuremath{-}J$ model at finite doping that respects an SU(2) symmetry: a symmetry previously known to be important at half filling. The mean-field phase diagram is found to be consistent with the phases observed in the cuprate superconductors, which contain $d$-wave superconductor, spin-gap, strange metal, and Fermi-liquid phases. The spin-gap phase is best understood as the staggered flux phase, which is nevertheless translationally invariant for physical quantities. The physical electron spectral function shows small Fermi segments at low doping that continuously evolve into the large Fermi surface at high-doping concentrations. The close relation between the SU(2) and the U(1) slave-boson theory is discussed. The low-energy effective theory for the low-lying fluctuations is derived and additional lying modes [which were overlooked in the U(1) theory] are identified.
145 citations
TL;DR: In this paper, the authors derived a geometric action for the tensionless (T = 0) string and discussed its symmetries and field equations, and showed that the Weyl symmetry of the usual tensile string is replaced by a global space-time conformal symmetry in the T→0 limit.
145 citations
TL;DR: In this article, it has been shown that hadrons containing a single heavy quark exhibit a new flavor-spin symmetry of QCD and exploit this symmetry to obtain model-independent absolutely normalized predictions for some heavy-baryon weak form factors at zero recoil.
145 citations